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Additional Keywords For CASSCF CalculationsMain.AdditionalKeywordsForCASSCFCalculations HistoryHide minor edits  Show changes to markup August 08, 2016, at 04:05 PM
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a) ORBITALS (=0, default): a list of orbital numbers, as printed after the SCF solution, is provided as a list of integers separated by spaces.
b) OCCUPATION (=1): the number of internal (i.e., doubly occupied) orbitals is provided for each irrep as a list of integers separated by one space and, on a new line, the list of active orbitals is provided for each irrep, as a list of integers separated by one space
a) CANONICAL (=0, default): use the HartreeFock wavefunction as a guess. For UHF orbitals, this corresponds to using alpha orbitals only.
b) CASCI (=1): starting from the HartreeFock orbitals, compute a CASCI wavefunction and use it as a guess. This might help convergence.
c) MODCASCI (=2): experimental use.
d) CORECASCI (=3): computes a CASCI guess using the core orbitals.
Advanced options
a) ILU/JACOBI (=0, default): use the incomplete LU decomposition (ILU) to precondition the Davidson iterations for the MO part. If the JacobiDavidson algorithm has been chosen, use the standard diagonal preconditioner for the first iterations and the ILU one to precondition the GMRES solution to the JacobiDavidson linear equations
b) JACOBI (=1): use the standard Davidson diagonalization, using a diagonal (i.e., Jacobi) preconditioner
c) ILU (=2): use the incomplete LU decomposition of the MO rotation Hessian to precondition the orbital updates in the microiterations. This is cheap and effective and is used as a default
d) EIG(=3): Explicitly diagonalize the MO rotation Hessian. This option is mainly for debugging purposes, but might be used with caution for tough cases.
